阴极防护下钢筋在模拟混凝土孔隙液中锈蚀的临界氯离子浓度  

Critical Chloride Ion Concentration of Steel Bar Corrosion in Simulated Concrete Pore Solution under Cathodic Protection

作　　者：李海洪[1] 方翔[1] 陈昊翔 张东方 LI Haihong;FANG Xiang;CHEN Haoxiang;ZHANG Dongfang(CCCC Fourth Harbour Engineering Institution Co.,Ltd.,Guangzhou 510230,China)

机构地区：[1]中交四航工程研究院有限公司,广州510230

出　　处：《腐蚀与防护》2024年第9期67-73,共7页Corrosion & Protection

摘　　要：通过电位和电流变化和表面观测,并结合电化学阻抗谱,研究了恒电位和恒电流阴极防护下钢筋在模拟混凝土孔隙液(饱和氢氧化钙溶液)中发生锈蚀的临界氯离子浓度。结果表明:在10 mA/m^(2)电流密度阴极防护下,导致钢筋发生腐蚀的临界氯离子浓度为0.03 mol/L,这与无阴极防护状态下相同。当阴极防护电流足够大(大于10 mA/m^(2))时,钢筋在模拟孔隙液中未发生腐蚀,不存在临界氯离子浓度;在恒电位阴极防护欠防护状态下,随着保护电位的正移,钢筋发生腐蚀的临界氯离子浓度逐渐增大;当氯离子添加浓度超过临界氯离子浓度时,钢筋会发生溶解,这是由于钢筋局部腐蚀导致电位负于保护电位;基于结构物安全考虑,在模拟孔隙液中钢筋的阴极防护宜采用恒电流控制。The critical chloride ion concentrations of corrosion of steel bar in simulated concrete pore solution(saturated calcium hydroxide solution)under constant potential and constant current cathodic protection were studied by means of potential and current change and surface observation,combined with electrochemical impedance spectroscopy.The results show that under the cathodic protection of 10 mA/m^(2) current density,the critical chloride ion concentration leading to corrosion of steel bar was 0.03 mol/L,which was the same as that without cathodic protection.When the cathodic protection current was large enough(greater than 10 mA/m^(2)),the steel bar was not corroded in the simulated pore solution,and there was no critical chloride ion concentration.In the under-protective state of constant potential cathode protection,with the positive shift of protection potential,the critical chloride ion concentration for corrosion of steel bars increased gradually.When the chloride ion concentration exceeded the critical chloride ion concentration,the steel bar would dissolve,because the potential was negative to the protection potential due to the localized corrosion of the steel bar;based on the safety of the structure,the cathode protection of the steel bar in the simulated pore solution should be controlled by constant current.

关 键 词：阴极防护 恒电位 恒电流 临界氯离子浓度 钢筋 

分 类 号：TG174[金属学及工艺—金属表面处理]